Attachment plug



Patented Nov. 2, 1943 UNITEDl STATES PATENT OFFICE 2,333,152 ATTACHMENTPLUG Nathan Chirels'tein, Maplewood, N. J. VApplication May '21, 1942,Serial No. 443,989 2 claims. `(el. 173-361.)

The invention here disclosed relates to electric attachment plugs andthe present application is a continuation-in-part of application forpatent Ser. No. 394,069 led May 19, 1941, Patent 2,292,049 issued August4, 1942.

Special objects of this invention are to enable use of particularlylight and inexpensive strip metal for the contact blades, Withoutsacrificing strength or stability and to enable easy and securefastening and connection of the wires to the blades, without solderingor requiring other fastening means.

These and other desirable objects are attained by the novel features ofconstruction, combinations and relations of parts hereinafter described,illustrated in the accompanying drawing and broadly covered in theclaims.

The drawing illustrates certain practical commercial embodiments of theinvention, it being appreciated that structure may be further modied andchanged in various ways, all within the intent and broad scope of theinvention as hereinafter defined and claimed.

Fig. 1 is a broken sectional View of an attachment plug embodyingfeatures of the invention.

Fig. 2 is a sectional view as on substantially the plane of line 2-2 ofFig. l.

Figs. 3 and 4 are detail views of a modification.

In the drawing, the plug base or plug cap 5, is shown as of the softrubber type having a cord passage t, at the back, opening into aterminal chamber l, and narrow blade passages S, extending through fromsaid chamber to blade seats 9, at the front.

The contact blades are shown in Figs. l and 2, as consisting each of astrip of quite thin metal doubled upon itself at the inner or terminalend to form a loop I9, for receiving the wire and the doubled portionsbent to provide the two offsets Il, l2, for disposition at opposite endsof the blade passage to anchor the blade in place and doubled back as atI3, to form the stem M, and divergent spring branch l5.

To avoid sharp exposed edges, the end of the inner layer at the tip ofthe spring branch may be bent inwardly and upwardly over the edge of theother layer, substantially as indicated at I6.

The Wires may be engaged and held in the terminal loops lll, in variousways. For example, the two layers may be sprung apart as by means of aninserted edged tool and the wire simply entered in between the layersand the loop allowed toclose `upon the inserted wire. In such case,parts of the wire could be rst-scraped bare, so that good electricalcontact would be effected upon the closing of the loop upon the insertedWire.

In the first illustration, the bared portion Il, of the wire is shownextended through the loop and brought up over the inner face of thecontact and passed through an opening I8, through to the outer side ofthe contact, thus to locate bared portions of the wire at opposite sidesof the contact, where it will be clamped by the resiliency of the plugmaterial against opposite faces and hence against both the layers of thetwo ply contact.

To facilitate entry of the Wire between the spring layers of thecontact, one or both layers of the doubled portions may be notched atone or more points as indicated at I9. When these notches are located atthe terminal loops, the wires may be used as wedges to assist inspreading the layers apart for receiving the Wires.

Because of the fact that the two layers are in flat face to faceengagement their full extent, except for the loop left at the terminalend to receive the wire, they fully reinforce each other and thisenables a very light, thin, exible and inexpensive form of metal stripto be used.

In the modified form of the invention illustrated in Figs. 3 and 4, thecontract blade is made of a single thickness of material, but providedwith a terminal loop 10a at the inner end of the same, similar to theloop I9 in the rst illustrated form of the invention.

Figs. 3 and 4 further show how the wire may be held by engaging aninsulated portion 20, of the Wire in the loop. The holding loop thenprovides a very effective strain relief. The insulated portion of theWire is squeezed and frictionally held in the spring loop, thisinsulated gripped portion of the wire extending transversely across thewidth of the blade and the wire leaving the loop through the notch lQa,at a sharp substantially right angle bend. The bared end portion lla ofthe wire likewise is sharply bent at the opposite edge of the blade andmay be there left free to engage one side of the blade or be passedthrough an opening 18a, to engage both sides of the blades when theblade is seated in its nal position in the rubber cap.

Instead of a notch at only one end, the terminal loop may be notched atboth ends to accommodate the Wire and avoid increasing the overall widthof the blade. Also, if desired, the end of the loop in the singlethickness form of the blade may be curled back somewhat to provide atapered entrance into the loop, enabling the insulated portion of thewire to be pulled into the loop with a Wedging action.

What is claimed is:

1. An attachment plug comprising a plug base and contacts havingterminal portions seated in said base and spring blade portionsprojecting from the base, said contacts consisting each of thin stripmetal folded on itself midlength into a Wire receiving loop and havingthe folded portions extending continuously in flat contacting relationfrom said wire receiving loop and said flat engaging portions sharplyfolded back upon themselves into a double layer spring branch, the endsof the strip being located in said double layer spring branch and thedoubled midlength portion of the strip which forms the Wire receivingloop constituting the Wire terminal portion of the contact and beinglocated Wholly Within the plug base.

2. An attachment plug comprising a plug base and contacts havingterminal portions seated in said base and spring blade portionsprojecting from the base, said contacts consisting each of thin stripmetal folded on itself midlength into a Wire receiving loop and havingthe folded portions extending continuously in ilat contacting relationfrom said Wire receiving loop and said at engaging portions sharplyfolded back upon themselves into a double layer spring branch, the endsof the strip being located in said double layer spring branch, with theend Which is outermost, extended and doubled around the other,underlying end to form a guard and the doubled midlength portion of thestrip which forms the wire receiving loop constituting the Wire terminalportion of the contact and being located Wholly within the plug base.

NATHAN CHIRELSTEIN.

